Nav: Home

Membrane lipids hop in and out of rafts in the blink of an eye

March 23, 2017

Researchers in Japan, India and France have found that molecules move into and out of a specialized region of the cell membrane, called the 'raft domain', at unexpectedly fast rates. The discovery was made possible by developing fluorescent compounds that are structurally similar to a special class of lipids called sphingomyelins, and by using a home-built fluorescent microscope sensitive enough to detect single fluorescent molecules.

Sphingomyelins are key molecules for the signalling functions and the formation of raft domains. But how they mediate the domains' signalling functions was unknown.

A team of researchers led by Akihiro Kusumi and Kenichi Suzuki of Kyoto University's Institute for Integrated Cell-Material Sciences (iCeMS) developed fluorescent compounds that are structurally similar to sphingomyelins and behave in a similar way. To make these fluorescent 'analogs', they attached a hydrophilic (water-preferring) fluorescent molecule to the 'head' part of synthetic sphingomyelin, with a hydrophilic linker group between them, without modifying a critical positive charge in the head group. This arrangement ensured that the fluorescent molecule was placed away from the interior of the cell membrane and did not interfere with the function of the sphingomyelin it was attached to or with the function of the cell membrane.

When the fluorescent sphingomyelin analogs were incorporated into the cell membrane of live mammalian cells in culture, they continually and very dynamically entered and exited from the cell membrane's raft domains. Raft domains are extremely small, around 1/1,000th of the width of a human hair. But they occupy 10 to 20% of the cell membrane area. Quite unexpectedly, the sphingomyelins spent only 12 and 50 milliseconds inside the raft domain before and after extracellular immunostimulation respectively. For comparison, the eye blinks in about 400 milliseconds.

Discovering the very short residency times of sphingomyelins in raft domains represents a large paradigm shift in the research field of cell biology, molecular immunology and molecular neuroscience. Previously, most researchers in these fields believed that raft-associated lipids, including sphingomyelins, were stably localized in raft domains.

"The results suggest that the fluorescent sphingomyelin analogs developed here will be extremely useful for studying sphingomyelin interactions with many other raft-associated molecules and raft domains as well as for understanding the mechanisms of cell membrane signalling and of the invasion of various pathogens," the researchers conclude.
-end-
The paper "Raft-based sphingomyelin interactions revealed by new fluorescent sphingomyelin analogs" appeared on March 22, 2017 in Journal of Cell Biology, with doi: 10.1083/jcb.201607086

The Institute for Integrated Cell-Material Sciences (iCeMS) at Kyoto University in Japan aims to advance the integration of cell and material sciences, both traditionally strong fields at the university, in a uniquely innovative global research environment. ICeMS combines the biosciences, chemistry, materials science and physics to create materials for mesoscopic cell control and cell-inspired materials. Such developments hold promise for significant advances in medicine, pharmaceutical studies, the environment and industry. http://www.icems.kyoto-u.ac.jp

Kyoto University

Related Cell Membrane Articles:

Across the cell membrane
Aquaporins and glucose transporters facilitate the movement of substances across biological membranes and are present in all kingdoms of life.
Location, location, location: The cell membrane facilitates RAS protein interactions
Many cancer medications fail to effectively target the most commonly mutated cancer genes in humans, called RAS.
New self-forming membrane to protect our environment
A new class of self-forming membrane has been developed by researchers from Newcastle University, UK.
Cell membrane proteins imaged in 3D
A team of scientists including researchers at the National Synchrotron Light Source II have demonstrated a new technique for imaging proteins in 3D with nanoscale resolution.
Researchers refute fifty-year old doctrine on cell membrane regulation
The cell membrane can be regarded as the boundary between life and non-life.
Proof of sandwiched graphene-membrane superstructure opens up a membrane-specific drug delivery mode
Researchers from the Institute of Process Engineering (IPE) of the Chinese Academy of Sciences and Tsinghua University (THU) proved a sandwiched superstructure for graphene oxide (GO) that transport inside cell membranes for the first time.
Membrane madness: The ins and outs of moving materials through the cell
The cell membrane is a fatty layer that forms a border between the inside of the cell, its various structures and the outside world.
Cell membrane as coating materials to better surface engineering of nanocarriers
Coating natural cell membranes on synthetic nanocarriers represents an innovative strategy of surface engineering.
Too-tight membrane keeps cells from splitting
Scientists uncover how one protein keeps conditions 'just right' so that cells can easily divide into two identical daughter cells.
How proteins become embedded in a cell membrane
Many proteins with important biological functions are embedded in a biomembrane in the cells of humans and other living organisms.
More Cell Membrane News and Cell Membrane Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Meditations on Loneliness
Original broadcast date: April 24, 2020. We're a social species now living in isolation. But loneliness was a problem well before this era of social distancing. This hour, TED speakers explore how we can live and make peace with loneliness. Guests on the show include author and illustrator Jonny Sun, psychologist Susan Pinker, architect Grace Kim, and writer Suleika Jaouad.
Now Playing: Science for the People

#565 The Great Wide Indoors
We're all spending a bit more time indoors this summer than we probably figured. But did you ever stop to think about why the places we live and work as designed the way they are? And how they could be designed better? We're talking with Emily Anthes about her new book "The Great Indoors: The Surprising Science of how Buildings Shape our Behavior, Health and Happiness".
Now Playing: Radiolab

The Third. A TED Talk.
Jad gives a TED talk about his life as a journalist and how Radiolab has evolved over the years. Here's how TED described it:How do you end a story? Host of Radiolab Jad Abumrad tells how his search for an answer led him home to the mountains of Tennessee, where he met an unexpected teacher: Dolly Parton.Jad Nicholas Abumrad is a Lebanese-American radio host, composer and producer. He is the founder of the syndicated public radio program Radiolab, which is broadcast on over 600 radio stations nationwide and is downloaded more than 120 million times a year as a podcast. He also created More Perfect, a podcast that tells the stories behind the Supreme Court's most famous decisions. And most recently, Dolly Parton's America, a nine-episode podcast exploring the life and times of the iconic country music star. Abumrad has received three Peabody Awards and was named a MacArthur Fellow in 2011.